CME FOR THE MONTH SEPT2013
MERS
MIDDLE EAST RESPIRATORY SYNDROME- CORONAVIRUS (MERS-COV).
Corona viruses are a
group of viruses that infect the respiratory tract of both humans and animals.
Some corona viruses affect the digestive system. The virus has a crown-like
projection on its surface, which is how it got its name. There are many
different species of the virus. Human corona virus was discovered in 1965 and
accounts for 10 percent to 30 percent of common colds. It affects all age
groups and is most common during the winter and early spring. In young children
and older people, human corona virus can affect the lower respiratory tract as
well. Many people get corona virus for a second time within four months after
having it the first time. Scientists believe this is because the antibodies
created to fight the corona virus only protect a person for four months. In
addition, there are many different types of human corona virus and the
antibodies from one type will not protect you from another type. The incubation
period of the virus -- meaning the time it is in the body before symptoms
appear -- is usually two to four days, and the infection caused by human corona
virus is usually mild. A relatively small amount of information is known about
human corona viruses because most of them do not grow in cultured cells, making
it difficult to study them. This
particular strain of corona virus has not been previously identified in humans.
There is very limited information on transmission, severity and clinical impact
with only a small number of cases reported thus far
The SARS outbreak in
2002 was believed to be caused by a new type of corona virus that was similar
to the one that affects cats. Due to its contagious nature, SARS became a world
epidemic, spreading to 32 countries and infecting 8,459 people. Many of the
people who contracted SARS also developed pneumonia, and over 800 people died
as a result of SARS.
Corona viruses are species in the genera of virus belonging to the subfamily Coronaviridae in the family Coronaviridae. Corona viruses primarily infect the upper respiratory and gastrointestinal tract of mammals and birds. Four to five different currently known
strains of corona viruses infect humans.
The most publicized human corona virus, SARS-CoV which causes SARS, has a unique
pathogenesis because it causes both upper and lower respiratory tract
infections and can also cause gastroenteritis. Corona viruses are believed to cause a significant percentage
of all common
colds in human adults. Corona
viruses cause colds in humans primarily
in the winter and early spring seasons. The significance and economic impact of
corona viruses as causative agents of the
common cold are hard to assess because, unlike rhinoviruses (another common cold virus), human corona viruses are difficult to
grow in the laboratory. Corona viruses can even cause pneumonia, either direct viral
pneumonia or a secondary bacterial pneumonia.
In 2003, following the
outbreak of Severe acute
respiratory syndrome (SARS) which had begun the
prior year in Asia, and secondary cases elsewhere in the world, the Organization issued a press release stating
that a novel corona virus identified by a number of laboratories was the
causative agent for SARS. The virus was officially named the SARS
corona virus (SARS-CoV).
The
epidemic resulted in over 8,000 infections, about 10% of which resulted in
death.[3] X-ray crystallography studies
performed at the Advanced Light Source of Lawrence Berkeley
National Laboratory have
begun to give hope of a vaccine against
the disease "since [the spike protein] appears to be recognized by the
immune system of the host." Corona viruses are enveloped RNA viruses from the Coronaviridae family and part of the Coronavirinaesubfamily. With its characteristic
surface, the virions appear as a crown like image under the electron microscope
and so the viruses are named after the Latin word corona, meaning 'crown' or 'halo'.
In animals the viruses infect the respiratory and
gastrointestinal systems as well as occasionally affecting the liver and the
neurological systems.
The human corona viruses mainly infect the upper respiratory
and gastrointestinal tract. They often result in upper respiratory tract
infections (simple colds) in humans, causing mild illnesses usually of short
lasting nature with a rhinitis, cough, sore throat, as well as fever.
Occasionally, the viruses are able to cause more
significant lower respiratory tract infections in human with pneumonia; this is
more likely in immunocompromised individuals, people with cardiopulmonary
illnesses, as well as the elderly and young children. Only very rarely do the
humans viruses cause severe disease, like sever acute respiratory syndrome.
The five corona viruses types which affect humans are alpha (229E and
NL63), beta (OC43), HKUI1 and SARS-CoV - although the latter is best considered
an animal virus that has only rarely infected humans.
In humans, the transmission of corona viruses between an infected individual and others can
occur via respiratory secretions. This can happen either directly through
droplets from coughing or sneezing, or indirectly through
touching contaminated objects or surfaces as well as close contact, such
as touching or shaking hands.
There are currently no vaccines or specific treatments for
the corona viruses . Hence, in order to reduce the risk and prevent the spread
of infections, simple preventative measure are: good respiratory hygiene,
including washing hands; avoiding touching one's eyes, mouth and nose;
sanitary disposal of oral and nasal discharges as well as avoiding contact with
sick people.
Corona viruses are a large family of viruses
that includes viruses that may cause a range of illnesses in humans, from the
common cold to SARS. Viruses of this family also cause a number of animal
diseases.
MIDDLE EAST RESPIRATORY SYNDROME
CORONAVIRUS
corona virus which is now called the Middle East
respiratory syndrome corona virus (MERS-CoV).
This new beta virus strain of an animal corona virus was
identified in September 2012 in individuals with severe acute respiratory
illness occurring in the Arabian Peninsula, some of whom were transferred for
care to hospitals in Europe. Retrospectively some infections have also been
detected in humans with severe acute respiratory illness in Jordan in the
spring of 2012.
This corona virus differs from the previously identified corona
viruses such as the SARS corona virus (SARS-CoV), which caused the 2003 SARS
outbreaks.
There is still much to be investigated, but it is
considered likely that this virus originated from an animal source.
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More on corona virus infections
In chickens, the infectious bronchitis
virus (IBV), a corona viruses ,
targets not only the respiratory tract but also the uro-genital tract. The
virus can spread to different organs throughout the chicken.
Corona viruses also cause a range of diseases in farm animals
and domesticated pets, some of which can be serious and are a threat to the
farming industry. Economically significant corona viruses of farm animals include porcine corona viruses (transmissible
gastroenteritis corona viruses , TGE) and bovine corona viruses , which both result in diarrhoea in young animals. Feline Corona viruses : two forms, Feline
enteric corona viruses is a pathogen of
minor clinical significance, but spontaneous mutation of this virus can result
in feline infectious
peritonitis (FIP), a disease
associated with high mortality. There are two types of canine corona viruses (CCoV), one that causes mild gastrointestinal disease and one that
has been found to cause respiratory disease. Mouse hepatitis virus (MHV) is a corona viruses that causes an epidemic murine illness with high mortality,
especially among colonies of laboratory mice. Prior to the discovery of
SARS-CoV, MHV had been the best-studied corona viruses both in
vivo and in vitro as well as at the molecular level.
Some strains of MHV cause a progressive demyelinating encephalitis in mice
which has been used as a murine model for multiple sclerosis. Significant research
efforts have been focused on elucidating the viral pathogenesis of these animal corona viruses , especially by virologists interested in veterinary and zoonotic diseases.
